The aims of the research activities proposed herein are twofold: 1) to evaluate the capacity for respiratory rhythm generation at multiple sites within the brainstem and, 2) to evaluate the neurophysiological underlying the ventilatory activity which may be supported by the bulbospinal portion of the central nervous system. In the context of the latter, we believe that examinations of bulbospinal respiratory rhythm generation will be fruitful since bulbospinal elements represent a potentially simpler respiratory controller and, by definition, an anatomically simpler entity than the entire pontile-bulbospinal complex. Experiments which will be conducted to fulfill the above two aims will have as one common objective, the reversible or permanent blockade of neural activity at the pontomedullary junction. Thus, by procedures to be described herein, respiratory patterns may be reversibly altered and segments of the brainstem and spinal cord reversibly isolated from other portions of the central nervous system. Respiratory-modulated activity within the "isolated neural segments" will be monitored by recording activity in peripheral and/or cranial nerves and activity of single respiratory-modulated brainstem units. We believe that results of studies proposed herein will provide significant insights into the mechanisms responsible for the neurogenesis of automatic ventilatory activity.